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UNITED STATES PATENT OErIcE.

RUDOLF SILBERBERG, OF JERSEY CITY, NEWV JERSEY, ASSIGNOR OF ONE- HALF TO HENRY W. HOOPS, JR., OF SAME PLACE.

PROCESS OF DYEING.

SPECIFICATION forming part of Letters Patent No. 320,820, dated June 23, 1885.

Application filed March 25, 1885. (No specimens.) Patented in Canada April 20, 1885, No. 21,458.

To aZZ whom it may concern:

Be it known that I, RUnoLE SILBERBERG, a citizen of the United States, residing at J ersey City, in the county of Hudson and State of New Jersey, hax e invented certain new and useful Improvements in the Manufacture of Mordants, of which the following is a specification.

My improvement relates to dyeing with aniline colors; and the object of my improvement is to secure upon the goods a strong and permanent aniline dye, and this I effect by applying to the fibers before subjecting them to the aniline dye a deposit of chromium oxide in the manner described hereinafter.

In carrying out my improvement in dyeing I proceed as follows: I first prepare a solution of oxalate of chromium in any suitable manner, the following being a mode of manufac- 2O ture which I have found to be effective. I first dissolve sixty-six pounds of bichromate of potash in ninety-three pints of boiling water and add fifty five pints of nitric acid of a strength of 36 Raum. I then prepare a second solution of twenty-nine pounds of oxalic acid in sixty pints of water, with the addition of sixteen pints of glyoerine of a strength of 28 Baum. The two solutions are added together and boiled until a dilute solu- 0 tion appearsof a clear-green color, after which the solution is allowed to stand until nitrate of potash is deposited as crystals, when the oxalate of chromium will be in solution in the liquor of a strength of to 38 Baum. In 3 5 using the mordant-liquor thus obtained to form a mordant I take twenty quarts of the said liquor diluted to 8 Baum and mix therewith seventeen and a half quarts of a solution of caustic soda of a strength of 20 0 Baum, and after the two are well mixed I add five quarts of water. The reaction which takes place in preparing the said mixture is indicated in thefollowing formula: Or,(O,HO,) 6+ 6Na, HO=Or,O,,+6O HO,Na.

In employing the mordant prepared as above set forth in dyeing fabrics containing cotton with aniline colors a portion of the said mordant is diluted with double its volume of cold water, and the fabric is soaked in the liquid for ten hours, the goods having been previously soaked in boiling water. The goods are then removed, washed well in running water, and are then dyed in the ordinary manner with any desired aniline dye, which will impart a strong, fast, and permanent color. By subjecting the goods to the action of the mordant the fibers are impregnated with chromic oxide, which acts upon the aniline color to fix the same upon the fibers.

\Vhile I have found that the above described means of securing the impregnating of the fibers with chromic oxide is-effective and readily carried out, I do not limit myself to the use of such means. as the permanent dyeing of cotton fabrics or goods containing 6 cotton with aniline colors can be effected by the impregnating of the fibers with chromate oxide in any manner before subjecting them to the aniline dye.

It will be seen that by the means above de- 7o scribed the dyeing of a cotton fabric is effected at a single operation of an extremely simple character, capable of being performed by any ordinary workman.

I donot here claim the manufacture of oxalate of chromium, nor of a mordant consisting of a mixture of oxalate of chromium and cans tic soda (potash) in solution, as these form the subjectsnnatter of separate applications for Letters Patent, bearing Serial No. 160,07 5,and No. 164,816.

I claim- The improvement in dyeing fabrics containing cotton with aniline dyes, the same consisting in first immersing the fabric in boiling water, and then immersing it in a mixture of a solution of oxalate of chromium and a solution of caustic soda, then washing the fabric, and then dyeingvvith an aniline dye in the usual manner, substantially as set forth.

In testimony whereof I have signed my name to this specification in the presence of two subscribing witnesses.

RUDOLF sinBERBE G.

"Witnesses:

W. O. DUVALL, CHARLES E. Fosrnn. 

